This invention relates generally to integrated gasification combined-cycle (IGCC) power generation systems, and more specifically to methods and systems for optimizing heat transfer between a gasifier syngas cooler and a shift system in the IGCC system.
At least some known IGCC systems include a gasification system that is integrated with at least one power producing turbine system. For example, known gasifiers convert a mixture of fuel, air or oxygen, steam, limestone, and/or other additives into an output of partially combusted gas, sometimes referred to as “syngas.” The hot combustion gases are supplied to the combustor of a gas turbine engine, which powers a generator that supplies electrical power to a power grid. Exhaust from at least some known gas turbine engines is supplied to a heat recovery steam generator that generates steam for driving a steam turbine. Power generated by the steam turbine also drives an electrical generator that provides electrical power to the power grid.
At least some known gasification processes use a separate shift heat recovery system with feed product exchangers. Such a configuration requires an external heat source for pre-heating gasification feed to start the exothermic reaction in the shift reactor. Pre-heating in this configuration causes the production of medium pressure and intermediate pressure steam, which has limited usefulness in other parts of the process and reduces total plant efficiency.